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41.
高空高速无人飞行器热控制系统设计 总被引:1,自引:0,他引:1
针对飞行时间短、速度和高度变化快、表面温度波动大的无人飞行器UAV(Unmanned Aerial Vehicles)热控制系统设计难题,提出了一种可解决实际工程问题的热分析计算方法.即把热天工况、冷天工况和标准天工况作为设计/试验工况;采用参考温度法、高超音速工程预测法或计算流体动力学CFD(Computational Fluid Dynamics)数值模拟法,确定了飞行器表面温度分布,并把其作为后续热分析数学模型的外边界条件;分析结构热容量对瞬态热载荷的影响,建立与之相应的边值问题方程,并采用有限差分法求解;根据高空高速飞行特点及瞬态热载荷值,确定仪器设备舱调温系统方案. 相似文献
42.
论述了空间积分声光相关器对脉冲调制连续波信号的瞬时响应,分析了从实时光电检测器中检测出的波形,该波形是脉冲宽度,加权函数参量和与脉冲位置相关的空间衍射光分布的函数。进一步提出了脉冲序列相关时的光分布关系并通过实验加以论证。 相似文献
43.
The rising demand for Unmanned Aerial Systems(UASs) to perform tasks in hostile environments has emphasized the need for their simulation models for the preliminary evaluations of their missions. The efficiency of the UAS model is directly related to its capacity to estimate its flight dynamics with minimum computational resources. The literature describes several techniques to estimate accurate aircraft flight dynamics. Most of them are based on system identification. This paper presents an alternative methodology to obtain complete model of the S4 and S45 unmanned aerial systems. The UAS-S4 and the UAS-S45 models were divided into four sub-models, each corresponding to a specific discipline: aerodynamics, propulsion, mass and inertia, and actuator. The‘‘aerodynamic" sub-model was built using the Fderivatives in-house code, which is an improvement of the classical DATCOM procedure. The ‘‘propulsion" sub-model was obtained by coupling a two-stroke engine model based on the ideal Otto cycle and a Blade Element Theory(BET) analysis of the propeller. The ‘‘mass and the inertia" sub-model was designed utilizing the Raymer and DATCOM methodologies. A sub-model of an actuator using servomotor characteristics was employed to complete the model. The total model was then checked by validation of each submodel with numerical and experimental data. The results indicate that the obtained model was accurate and could be used to design a flight simulator. 相似文献
44.
对空间碎片检视或抓捕操控中的悬停控制及燃耗问题进行了研究。通过C W方程,建立任务星近距随遇定点悬停控制模型,通过设计状态反馈控制器分析定点悬停的可控性以及推控要求,结果表明近距悬停需要与悬停位置相关的两个正交方向上的常值连续推力控制量,以及用于抵抗扰动的三轴向上的反馈变推力控制量。分析了近距随遇悬停的推控分系统配置,建立了长时近距随遇悬停的燃耗及燃耗速率的数学模型,最后分析了既满足安全距离需求、又满足悬停方位需求的最小悬停燃耗模型。 相似文献
45.
Mikhail Sachkov Boris Shustov Ana Ines Gómez de Castro 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2014
During last three decades, astronomers have enjoyed continuous access to the 100–300 nm ultraviolet (UV) spectral range where the resonance transitions of the most abundant atoms and ions (at temperatures between 3000 and 300 000 K) reside. This UV range is not accessible from ground-based facilities. The successful International Ultraviolet Explorer (IUE) observatory, the Russian ASTRON mission and successor instruments such as the Galaxy Evolution Explorer (GALEX) mission or the COS and STIS spectrographs on-board the Hubble Space Telescope (HST) prove the major impact of observations in the UV wavelength range in modern astronomy. Future access to space-based observatories is expected to be very limited. For the next decade, the post-HST era, the World Space Observatory – Ultraviolet (WSO–UV) will be the only 2-m class UV telescope with capabilities similar to the HST. WSO–UV will be equipped with instruments for imaging and spectroscopy and it will be a facility dedicated, full-time, to UV astronomy. In this article, we briefly outline the current status of the WSO–UV mission and the science management plan. 相似文献
46.
国家数值风洞高超声速流动模拟软件HyFLOW的研制对打破国外同类软件的技术壁垒具有重要意义。与国外DPLR软件进行了对比研究,同时系统介绍了HyFLOW软件求解器的数值方法、物理化学模型以及壁面催化特性计算模型等主要方法,采用典型算例对有限催化模型进行了数值验证,最后基于LENS风洞试验146 mm返回器标模外形开展了高超声速气动热特性数值模拟。研究结果表明,HyFLOW软件在高超声速热化学非平衡流动模拟与评估方面的气动力计算精度高,与国外同类软件DPLR相当,同时其壁面催化条件下的气动热计算精度可靠,可信度高。 相似文献
47.
This paper presents the novel use of the particle swarm optimization(PSO)to generate the end-to-end trajectory for hypersonic reentry vehicles in a quite simple formulation.The velocitydependent bank angle profile is developed to reduce the search space of unknown parameters based on the constrained PSO algorithm.The path constraints are enforced by setting the fitness function to be infinite on condition that the particles violate the maximum allowable values.The PSO algorithm also provides a much easier means to satisfy the terminal conditions by adding penalty terms to the fitness function.Furthermore,the approximate reentry landing footprint is fast constructed by incorporating an interpolation model into the standardized bank angle profiles.Numerical simulations demonstrate that the PSO method is a feasible and flexible tool to generate the end-to-end trajectory and landing footprint for hypersonic reentry vehicles. 相似文献
48.
Martin Schlueter 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2014
A numerical study of the MIDACO optimization software on the well known GTOP benchmark set, published by the European Space Agency (ESA), is presented. The GTOP database provides trajectory models of real-world interplanetary space missions such as Cassini, Messenger or Rosetta. The trajectory models are formulated as constrained nonlinear optimization problems and are known to be difficult to solve. 相似文献
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